lithium-fluoride and potassium-fluoride

The interaction between nuclear graphite and molten fluoride salts (46.5 mol % LiF/11.5 mol % NaF/42 mol % KF) is investigated by synchrotron X-ray diffraction and C K-edge X-ray absorption near-edge structure (XANES). It is found that there are a large number of H atoms in IG-110 nuclear graphite, which is attributed to the residual C-H bond after the graphitization process of petroleum coke and pitch binder. The elastic recoil detection analysis indicates that H atoms are uniformly distributed in IG-110 nuclear graphite, in excellent agreement with the XANES results. The XANES results indicate that the immersion in molten fluoride salts at 500 °C led to H atoms in nuclear graphite partly substituted by the fluorine from fluoride salts to form C-F bond. The implications of these findings are discussed.

Topics: Fluorides; Graphite; Hydrogen; Ions; Lithium Compounds; Potassium Compounds; Salts; Sodium Fluoride; Synchrotrons

Thermoluminescent (TL) properties of two concentration series lithium potassium yttrium fluoride doped with praseodymium (LiKYF5:Pr3+) and potassium yttrium fluoride doped with thulium (KYF4:Tm3+) have been investigated after gamma and neutron irradiation. The main purpose of this research is to see whether these materials are suitable for gamma and/or neutron dosimetry purposes. It has been found that the compounds of both series are sensitive to 60Co gamma radiation. A maximal TL sensitivity is found for LiKY0.99Pr0.01F5 and KY0.99Tm0.01F4. However, for this doping level the intensity of the TL glow peak is about 7 times less than that for LiF:Mg,Ti (TLD-700). The TL sensitivity to thermal neutrons is relatively higher than that to 60Co photons. No TL sensitivity to fast neutrons was observed.

Topics: Crystallization; Fluorides; Gamma Rays; Lithium Compounds; Neutrons; Photons; Potassium Compounds; Praseodymium; Radiochemistry; Sensitivity and Specificity; Thermoluminescent Dosimetry; Thulium; Yttrium

The interactions of alkali fluorides with D-xylose have been studied by X-ray diffraction (XRD), infrared spectroscopy (IR), nuclear magnetic resonance (NMR, 1H and 13C) and atomic absorption spectrophotometry. KF and CsF form complexes with D-xylose in a 1:1 molar ratio. These complexes can be obtained by solid state milling the reactants in an agate mortar or from methanolic solutions of the sugar and the salt. LiF and NaF do not form complex with D-xylose. IR and XRD prove the identical nature of the complexes obtained by milling and from solution. IR spectra indicate strong perturbation of the OH stretching vibrations with considerable shifts to lower frequencies, which must be caused by strong hydrogen bond formation to the fluorine anion. The perturbations of C-O bond are weak, indicating that cation binding to the oxygen atoms is not the main interaction responsible for the complex formation. 1H NMR spectra of the D-xylose-KF complex dissolved in deuterium oxide is equal to that of pure D-xylose, indicating the destruction of the complex in solution. The complex is stable in DMSO, and 13C spectra of the complex in DMSO-d6 and in solid state (CPMAS) spectra are in accordance with the observed interactions in the IR spectra. As far as we know, this is the first report of a sugar-halide salt complex in which the anion instead of the cation provides the binding forces.

Topics: Alcohols; Alkalies; Carbohydrates; Cations; Cesium; Crystallization; Fluorides; Lithium Compounds; Magnetic Resonance Spectroscopy; Potassium Compounds; Salts; Sodium Fluoride; Solutions; Spectrophotometry, Infrared; X-Ray Diffraction; Xylose